X‐MAN™ (gene‐X Mutant And Normal) cell lines provide genetically defined, patient‐relevant, predictive in vitro models of genetic disease. We are further extending their application within targeted drug discovery with the development of new reporter disease models using our GENESIS™ gene engineering technology (Figure 1). These models combine X‐MAN™ cell lines with the endogenous gene reporting capabilities in the form of NanoLuc™ luciferase and HaloTag® reporter technologies.